Segmented films with high strength seams

ABSTRACT

Unitary films and laminates thereof are provided having at least first and second film segments which extend adjacent one another and are permanently joined together. The first and second film segments are joined at an interface, wherein at the interface a tip of the second segment overlaps the first segment in the cross-direction of the film. The film has a thickness “T” at the tip of the second segment, and the second segment has a thickness “t” at a distance T in the cross direction from the tip of the second segment. The ratio T/t is suitably greater than about 3. The unitary films and laminates thereof are well suited, for example, for use as outer covers in personal care articles.

RELATED APPLICATION

The present application is a divisional application of U.S. patentapplication Ser. No. 12/982,979, by Wing-Chak Ng, filed on Dec. 31,2010, the contents of which are incorporated herein.

BACKGROUND OF THE INVENTION

Thin films have a wide variety of applications including use as outercovers for personal care products (e.g. diapers or incontinencegarments), medical garments, industrial workwear and so forth. Inaddition, laminates of such films have found use in various bodilyarticles as well as numerous other applications. The films can providethe desired barrier properties to the article while other materialslaminated thereto can provide additional desired characteristics such asstrength, abrasion resistance and/or good hand.

Segmented films can be used to provide different properties to differentareas of a product. For example, it may not be necessary to have highbreathability and good stretch and recovery properties in the same areaof the film. In that case, a segmented film having elastic segments onthe outer edges and a breathable barrier segment in the center can beused as an outercover film for a personal care absorbent product.

However, segmented films may be weak at the interface between thesegments. The weak interface can be prone to tearing. The weakness canbe due to lack of cohesiveness between the different materials used inthe different segments of the film.

Thus, there exists a need for an improved segmented film having improvedstrength at an interface between the segments of the film.

SUMMARY OF THE INVENTION

The aforesaid needs are fulfilled and the problems experienced by thoseskilled in the art overcome by the segmented film of the presentinvention which includes a first film segment having a first compositionand a second film segment having a second composition, the first andsecond film segments being joined at an interface extending in themachine direction of the segmented film. At the interface a tip of thesecond segment overlaps the first segment in the cross-direction of thefilm. The film has a thickness “T” at the tip of the second segment, andthe second segment has a thickness “t” at a distance T in the crossdirection from the tip of the second segment. The ratio T/t is suitablygreater than about 3. Desirably, the segmented film has a substantiallyuniform thickness and the first and second segments extend adjacent oneanother continuously in the machine-direction of the film.

In another aspect, the first or second film segment may include amicroporous film. In one embodiment, the composition of the first orsecond film segment includes thermoplastic polymer and filler. Thethermoplastic polymer may be an inelastic polyolefin polymer. Desirably,the filler is distributed throughout the first film segment. Moredesirably, the first or second film segment has micropores adjacent thefiller.

In a further aspect, the first or second film segment may include anelastic polymer selected from the group consisting of polyolefinelastomers, styrenic block copolymers, polyurethanes, polyesters,polyamides, vinyl acetates, acrylates and blends thereof.

In a further aspect, the segmented films of the present invention can belaminated or fixedly attached to a sheet such as, for example, anonwoven web, woven fabric, and so forth. As used herein, the term“sheet” refers to a layer of material which can be a woven material,knitted material, scrim, nonwoven web or other like material. Inaddition, the films and film laminates of the present invention are wellsuited for use in personal care articles, protective apparel, protectivecovers and infection control products. As an example, personal carearticles of the present invention can include (i) a liquid pervioustopsheet; (ii) an outer cover comprising a segmented film or filmlaminate as described herein; and (iii) an absorbent core positionedbetween the outer cover and topsheet. The first and second film segmentscan be selectively positioned within the article to provide the desiredattributes such as body conformance, regional water vapor transmissionrates and/or aesthetics.

In another embodiment, a method of forming a segmented film includes thesteps of providing first and second polymer compositions to a segmentedfeedblock; transferring the first and second polymer compositions to afilm die; and co-extruding from the film die a segmented film comprisinga first film segment of the first polymer composition and a second filmsegment of the second polymer composition, the first and second filmsegments being joined at an interface, wherein at the interface a tip ofthe second film segment overlaps the first film segment in thecross-direction of the film, and wherein the film has a thickness “T” atthe tip of the second film segment, and the second film segment has athickness “t” at a distance T in the cross direction from the tip of thesecond film segment, and wherein the ratio T/t is greater than about 3.

In a further embodiment, a method of forming a segmented film includesthe steps of providing first and second polymer compositions to asegmented feedblock that feeds the first and second polymer compositionsto a film die; and co-extruding from the film die a segmented filmcomprising a first film segment of the first polymer composition and asecond film segment of the second polymer composition, wherein the firstand second polymer compositions flow together in the film diesubstantially in a cross direction prior to exiting the film die in amachine direction, and further wherein the first and second filmsegments extend adjacent one another continuously in themachine-direction.

Other features and aspects of the present invention are described inmore detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures in which:

FIG. 1 is a top, plan view of a multi-segmented film of the presentinvention;

FIG. 1A is a cross-sectional view of the multi-segmented film of FIG. 1taken at 1A-1A;

FIG. 2 is an SEM photograph of a cross-section of an exemplary segmentedfilm.

FIG. 3 is an SEM photograph of a cross-section of another exemplarysegmented film.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation, not limitation of theinvention. In fact, it will be apparent to those skilled in the art thatvarious modifications and variations may be made in the presentinvention without departing from the scope or spirit of the invention.For instance, features illustrated or described as part of oneembodiment, may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention cover suchmodifications and variations.

In reference to FIGS. 1 and 1A, a unitary segmented film 32 having amachine direction (MD) and a cross direction (CD), further having afirst surface 18 and a second surface 20 parallel or generally parallelto the first surface, is shown having at least a first segment 12attached to at least a second segment 14 with an interface or seam 16where the first segment is attached to the second segment. The firstsegment 12, second segment 14, and the seam 16 generally runcontinuously in the machine direction. At the interface 16 the secondsegment 14 overlaps the first segment 12 in the cross direction, thatis, the first segment extends past the second segment in the crossdirection. The second segment 14 extends past or overlaps the firstsegment 12 to a tip 22 of the second segment. The tip 22 of the secondsegment 14 is the part of the second segment that extends the farthestin the cross direction into the first segment 12.

The extent to which the second segment overlaps the first segment may beassessed by comparing the thickness “T” of the film 32 at the tip 22 ofthe second segment 14 to the thickness “t” of the second segment at adistance “T” in the cross-direction from the tip. Desirably, the ratioT/t is large, indicating a greater overlap of the first segment 12 andsecond segment 14 at the interface 16. In some embodiments, the ratioT/t is suitably greater than about 3, more suitably greater than about5, and even more suitably greater than about 7. In other embodiments,the ratio T/t is suitably in a range from about 3 to about 50, moresuitably in a range from about 5 to about 50, even more suitably in arange from about 7 to about 50. In another embodiment, the ratio T/t issuitably in a range from about 3 to about 30, more suitably in a rangefrom about 6 to about 30, and even more suitably in a range from about10 to about 30.

Desirably, the first segment 12 comprises at least about 10% of the areaof the segmented film 32 and, even more desirably, comprises betweenabout 20% and about 80% of the area of the segmented film 32. Althoughthicker segmented films are possible, the unitary segmented filmdesirably has a maximum film thickness less than about 50 microns andstill more desirably has a maximum film thickness between about 10microns and about 35 microns. The first and second segments 12 and 14can be selected to comprise distinct films having varied attributes suchas, for example, distinct breathability and/or elastic properties. Asused herein, the term “elastic” generally refers to material which, uponapplication of a biasing force, is extensible or elongatable in at leastone direction and returns substantially to its original dimensionsimmediately after the biasing force is removed.

Segmented films, as described herein, may have distinct film segmentswhich exhibit varied levels of breathability and/or elasticity can beformed by various methods. Segmented films can be formed by coextrudingthe respective adjacent segments such as, for example, using the methodand apparatus for forming films as disclosed in U.S. Pat. No. 4,533,510to Nissel et al., the entire contents of which are incorporated hereinby reference. Film dies for forming side-by-side coextruded films arecommercially available from Extrusion Dies Industries, LLC of ChippewaFalls, Wis. and Cloeren Inc. of Orange, Tex. The desired components ofthe respective film segments can be separately mixed, heated and thencoextruded into the respective side-by-side segments of a unitarysegmented film. The film may be made by any one of a variety of filmforming processes known in the art such as, for example, by using eithercast or blown film equipment. Desirably, the first and secondcompositions are introduced to a segmented feed block prior to enteringthe film die. The segmented feed block allows contact between the firstand second compositions prior to the compositions entering the film die.This early contact between the first and second compositions is believedto result in the extended overlap of the first and second segments atthe interface between the segments. In one embodiment, a feed blocksuitable for making layered films from one or more polymer compositionsis rotated 90 degrees with respect to the die body to provide segmentedfilms rather than layered films. Suitable feed blocks, such as microfeed blocks or modular feed blocks, may be obtained from RandcastleExtrusion Systems, Inc., of Cedar Grove, N.J. The extruded segmentedfilm is then processed as desired.

In one aspect, the unitary segmented film can be stretched in at leastone direction, thereby reducing the film gauge or thickness. Asdiscussed in more detail herein below, a particularly desirable film orfilm segment is a microporous stretched filled-film. Such microporousfilled-film segments may include at least a thermoplastic polymer andfiller. With regard to microporous stretched filled-films, in additionto reducing the film thickness, stretching may also impart porosity tothe film and may form a micropore network therein which renders thefilms breathable. As used herein the term “polymer” generally includesbut is not limited to, homopolymers, copolymers, such as for example,block, graft, random and alternating copolymers, terpolymers, etc. andblends and modifications thereof. Furthermore, unless otherwisespecifically limited, the term “polymer” includes all possible spatialconfigurations of the molecule. These configurations include, but arenot limited to isotactic, syndiotactic and random symmetries. As usedherein the term “blend” means a mixture of two or more polymers whilethe term “alloy” means a sub-class of blends wherein the components areimmiscible but have been compatibilized. As used herein “filler” ismeant to include particulates and other forms of materials which can beadded to the polymer and which will not chemically interfere with oradversely affect the extruded film but is able to be dispersedthroughout the film. The filler particles may optionally be coated witha fatty acid, such as stearic acid or behenic acid, and/or othermaterial in order to facilitate the free flow of the particles (in bulk)and their ease of dispersion into the polymer. Stretching can beachieved by various means known to those skilled in the art. Films canbe stretched or oriented in either or both the MD and CD. As usedherein, the term “machine direction” or MD means the direction in whicha film or fabric is produced. The term “cross machine direction” or CDmeans the direction associated with the width of film or fabric, i.e. adirection generally perpendicular to the MD. As examples, machinedirection orientation equipment is commercially available from vendorssuch as the Marshall and Williams Company of Providence, R.I. andbiaxial orientation equipment is commercially available from BrucknerGMBH of Siegsdorf, Germany. As a further example, the films can bestretched utilizing grooved or patterned rollers such as, for example,those described in U.S. Pat. No. 4,153,751 to Schwarz, U.S. Pat. No.5,028,289 to Rasmussen, and U.S. Pat. No. 6,368,444 to Jameson et al.;the entire contents of the aforesaid references are incorporated hereinby reference. When using one or more elastic segments it may beadvantageous to anneal or heat set the stretched segmented film while inthe stretched or tensioned state in order to set the elastic segment andreduce the potential for puckering of the film caused by the retractiveforce of the elastic segments. In addition, when using films which havebeen independently pre-formed and subsequently joined, it is possible toprocess the films, for example to stretch-thin the films and so forth,either prior to or after permanently joining the respective segmentstogether to form a unitary segmented film.

There exists a wide variety of polymers suitable for use with thepresent invention. The segments of the segmented film can be made fromany thermoplastic polymer suitable for film formation and desirablycomprise thermoplastic polymers which can be readily stretched to reducethe film gauge or thickness. Film forming polymers suitable for use withthe present invention, alone or in combination with other polymers,include, by way of example only, polyolefins, ethylene vinyl acetate(EVA), ethylene ethyl acrylate (EEA), ethylene acrylic acid (EAA),ethylene methyl acrylate (EMA), ethylene normal butyl acrylate (EnBA),polyester, polyethylene terephthalate (PET), nylon, ethylene vinylalcohol (EVOH), polystyrene (PS), polyurethane (PU), polybutylene (PB),polyether esters, polyether amides, and polybutylene terephthalate(PBT).

Suitable polymers for forming one or more of the film segments, include,but are not limited to, polyolefins. A wide variety of polyolefinpolymers exist and the particular composition of the polyolefin polymerand/or method of making the same is not believed critical to the presentinvention and thus both conventional and non-conventional polyolefinscapable of forming films are believed suitable for use in the presentinvention. As used herein, “conventional” polyolefins refers to thosemade by traditional catalysts such as, for example, Ziegler-Nattacatalysts. Suitable polyethylene and polypropylene polymers are widelyavailable and, as one example, linear low density polyethylene isavailable from The Dow Chemical Company of Midland, Mich. under thetrade name AFFINITY and conventional polypropylene is available fromExxonMobil Chemical Company of Houston, Tex. In addition, elastic andinelastic polyolefins made by “metallocene”, “constrained geometry” or“single-site” catalysts are also suitable for use in the presentinvention. Examples of such catalysts and polymers are described in U.S.Pat. No. 5,472,775 to Obijeski et al.; U.S. Pat. No. 5,451,450 toErderly et al.; U.S. Pat. No. 5,278,272 to Lai et al.; U.S. Pat. No.5,272,236 to Lai et al.; U.S. Pat. No. 5,204,429 to Kaminsky et al.;U.S. Pat. No. 5,539,124 to Etherton et al.; and U.S. Pat. No. 5,554,775to Krishnamurti et al.; the entire contents of which are incorporatedherein by reference. The aforesaid patents to Obijeski and Lai teachexemplary polyolefin elastomers and, in addition, exemplary low densitypolyethylene elastomers are commercially available from The Dow ChemicalCompany under the trade name AFFINITY, from ExxonMobil Chemical Company,under the trade name EXACT, and from Dupont Dow Elastomers, L.L.C. underthe trade name ENGAGE. Moreover, exemplary propylene-ethylene copolymerplastomers and elastomers are commercially available from The DowChemical Company under the trade name VERSIFY and ExxonMobil ChemicalCompany under the trade name VISTAMAXX.

In addition, stereoblock polymers are also believed well suited forpracticing the present invention. The term “stereoblock polymer” refersto polymeric materials with controlled regional tacticity orstereosequencing to achieve desired polymer crystallinity. Bycontrolling the stereoregularity during polymerization, it is possibleto achieve atacticisotactic stereo blocks. Methods of forming polyolefinstereoblock polymers are known in the art and are described in thefollowing articles: G. Coates and R. Waymouth, “OscillatingStereocontrol: A Strategy for the Synthesis of Thermoplastic ElastomericPolypropylene” 267 Science 217-219 (January 1995); K. Wagener,“Oscillating Catalysts: A New Twist for Plastics” 267 Science 191(January 1995). Stereoblock polymers and methods of their production arealso described in U.S. Pat. No. 5,594,080 to Waymouth et al., U.S. Pat.No. 5,208,304 to Waymouth and European Patent Application PublicationNo. 0475306 A1. As indicated above, by controlling the crystallinity ofolefins it is possible to provide polymers exhibiting unique tensilemodulus and/or elongation properties. In addition, polyolefincopolymers, and in particular propylene-ethylene copolymers, are alsosuitable for use with the present invention. As but one example,exemplary propylene-ethylene copolymers can comprise multi-step reactorproducts wherein an amorphous ethylene propylene random copolymer ismolecularly dispersed in a predominately semi-crystalline high propylenemonomer/low ethylene monomer continuous matrix. Examples of suchpolymers are described in U.S. Pat. No. 5,300,365 to Ogale; U.S. Pat.No. 5,212,246 to Ogale and U.S. Pat. No. 5,331,047 to Giacobbe. Suchpolymers are commercially available from LyondellBasell under the tradename CATALLOY polymers.

Other exemplary commercially available elastomeric materials include,but are not limited to, the following polymers: elastomericpolyurethanes such as, for example, those available under the trade nameESTANE from Lubrizol Advanced Materials, Inc.; elastomeric polyetheresters such as, for example, those available under the trade name HYTRELfrom E. I. DuPont De Nemours & Company, and those available under thetrade name ARNITEL available from DSM of Sittard, Holland (formerlyavailable from Akzo Plastics of Arnhem, Holland); and elastomericpolyether amides commercially available from Arkema, Inc. under thetrade name PEBAX. As additional examples, suitable thermoplasticelastomers also include those made from block copolymers having thegeneral formula A-B-A′ where A and A′ are each a thermoplastic polymerendblock which contains a styrenic moiety such as a poly(vinyl arene)and where B is an elastomeric polymer midblock such as a conjugateddiene or a lower alkene polymer. Further, exemplary block copolymersinclude A-B-A-B tetrablock polymers having an isoprene monomer unithydrogenated to a substantially poly(ethylene-propylene) monomer unitsuch as astyrene-poly(ethylene-propylene)-styrene-poly(ethylene-propylene)elastomeric block copolymer. Examples of such styrene-olefin blockcopolymers include styrene-(ethylene-butylene),styrene-(ethylene-propylene), styrene-(ethylene-butylene)-styrene,styrene-(ethylene-propylene)-styrene,styrene-(ethylene-butylene)-styrene-(ethylene-butylene),styrene-(ethylene-propylene)-styrene-(ethylene-propylene), andstyrene-ethylene-(ethylene-propylene)-styrene. These block copolymersmay have a linear, radial or star-shaped molecular configuration. Asspecific examples, exemplary elastomers can comprise(polystyrene/poly(ethylene-butylene)/polystyrene) block copolymersavailable from the Kraton Polymers LLC under the trade name KRATON aswell as polyolefin/KRATON blends such as those described in U.S. Pat.Nos. 4,663,220, 4,323,534, 4,834,738, 5,093,422, 5,304,599, and5,332,613, the entire contents of the aforesaid references areincorporated herein by reference. Still other suitable copolymersinclude the S-I-S and S-B-S elastomeric copolymers available from DexcoPolymers of Houston, Tex. under the trade designation VECTOR®.

Other additives may also be incorporated into the film, such as meltstabilizers, crosslinking catalysts, pro-rad additives, processingstabilizers, heat stabilizers, light stabilizers, antioxidants, heataging stabilizers, whitening agents, antiblocking agents, bondingagents, tackifiers, viscosity modifiers, etc. Examples of suitabletackifier resins may include, for instance, hydrogenated hydrocarbonresins. REGALREZ™ hydrocarbon resins are examples of such hydrogenatedhydrocarbon resins, and are available from Eastman Chemical. Othertackifiers are available from ExxonMobil under the ESCOREZ™ designation.Viscosity modifiers may also be employed, such as polyethylene wax(e.g., EPOLENE™ C-10 from Eastman Chemical). Phosphite stabilizers(e.g., IRGAFOS available from Ciba Specialty Chemicals of Terrytown,N.Y. and DOVERPHOS available from Dover Chemical Corp. of Dover, Ohio)are exemplary melt stabilizers. In addition, hindered amine stabilizers(e.g., CHIMASSORB available from Ciba Specialty Chemicals) are exemplaryheat and light stabilizers. Further, hindered phenols are commonly usedas an antioxidant in the production of films. Some suitable hinderedphenols include those available from Ciba Specialty Chemicals of underthe trade name “Irganox®”, such as Irganox® 1076, 1010, or E 201.Moreover, bonding agents may also be added to the film to facilitatebonding of the film to additional materials (e.g., nonwoven web).Typically, such additives (e.g., tackifier, antioxidant, stabilizer,etc.) are each present in an amount from about 0.001 wt. % to about 25wt. %, in some embodiments, from about 0.005 wt. % to about 20 wt. %,and in some embodiments, from 0.01 wt. % to about 15 wt. % of the film.

As indicated above, the first segment of the segmented film may includea breathable film. As used herein, the term “breathable” or“breathability” refers to the water vapor transmission rate (WVTR) of anarea of fabric which is measured in grams of water per square meter perday (g/m²/24 hours). WVTR results are reported in grams/squaremeter/day. Further, as used herein the term “breathable” refers to afabric having a WVTR of at least 800 g/m²24 hours. Various breathablefilms are suitable for use with the present invention, including bothmicroporous and monolithic (i.e. non-porous) films. Breathable filmscomprising the first segment or segments can be elastic or inelastic anddesirably have a WVTR of at least about 800 g/m²/day, and more desirablyhaving a WVTR in excess of about 1500 g/m²/day, and still more desirablya WVTR in excess of about 3500 g/m²/day, and even more desirably a WVTRof about 5000 g/m²/day or more. In one aspect, the first segments can beinelastic or less-elastic than the second segment and may exhibit higherbreathability levels relative to the second segments before aperturing.Monolithic or non-microporous breathable films can exhibit goodbreathability when they comprise polymers which inherently have goodwater vapor transmission rates (i.e., polymers which allow water vaporto readily diffuse through the film) such as, for example,polyurethanes, polyether esters, polyether amides, EMA, EEA, EVA and thelike. Examples of breathable microporous films suitable for use as oneor more segments of the segmented film include, but are not limited to,those described in the following references: U.S. Pat. No. 5,695,868 toMcCormack; U.S. Pat. No. 6,075,179 to McCormack et al.; U.S. patentapplication Ser. No. 08/722,726 filed Oct. 1, 1996 to McCormack et al.;U.S. patent application Ser. No. 08/882,712 filed Jun. 25, 1997 toMcCormack et al.; U.S. Pat. No. 6,111,163 to McCormack et al.; U.S. Pat.No. 6,045,900 to Haffner et al.; U.S. patent application Ser. No.08/843,147 filed Apr. 25, 1997 to Gwaltney et al; and U.S. patentapplication Ser. No. 09/122,326 filed Jul. 24, 1998 to Shawver et al;U.S. Pat. No. 4,777,073 to Sheth; and U.S. Pat. No. 4,867,881 to Kinzer;the entire contents of the aforesaid references are incorporated hereinby reference.

The second segments can be non-breathable or breathable film segments.In addition, the second segments can be elastic or inelastic films. Inone embodiment, the second segments are elastic films and may compriseone or more elastic polymers. The second segments can comprise filmssimilar to those described above with respect to the first segments.However, the composition and/or structure of the first segment isdistinct from that of the second segment and the specific compositionand/or structure of the first and second segments will be selected withrespect to one another to achieve the desired functional and/oraesthetic attributes of the unitary, segmented film. The particular filmcomposition and/or structure of the respective segments can be selectedwith respect to various considerations such as end use, cost,durability, strength, shelf and product life expectancy, etc.

In one aspect of the invention, a segmented film can comprise a filmhaving varied regional breathability. As an example, the first segmentscan include breathable films separated along a length of the film by thesecond segments. The second segments can comprise either breathable ornon-breathable films prior to aperturing. In order to achieve a unitaryfilm having varied regional breathability first segments can be selectedto have a higher or lower WVTR relative to the second segments afteraperturing. WVTRs of adjacent segments can vary in accord with theselected film composition and/or structure thereof, thereby yielding afilm having adjacent segments with distinct levels of breathability. Inthis regard, first and second segments can have distinct WVTRs byselecting different film compositions for the respective segments. As anexample, first segments can have a higher weight percent of filler thansecond segments. Thus, stretching of the filled film creates a segmentedfilm having first breathable segments and second breathable segmentswherein the WVTR of first segments are higher than the WVTR of secondsegments, at least prior to aperturing. Additionally and/oralternatively, first and second segments can comprise different types offiller materials. The WVTRs of the respective segments can thus bevaried in accord with the desired application of the segmented film.High and low breathability segments can be strategically located withinthe unitary segmented film to achieve the desired breathability levelsin selected locations.

In a further aspect, it may be desirable to have each of the segmentscomprise an opaque film. This may be aesthetically desirably in certainarticles, such as diapers, to mask a soiled absorbent core. Opacifyingfillers can be included within one or more of the segments as needed inorder to create a segmented film which is uniformly opaque. However, theweight percent and/or type of filler can be varied amongst respectivesegments in order to selectively achieve disparate breathability levelswhile having substantially uniform opacity. As a specific example, thefirst segments may be a highly breathable microporous LLDPE film havingCaCO₃ filler particles and second segments may be a less breathable andless porous LLDPE film having TiO₂ filler particles.

As a further example, the first and second segments can includedifferent polymers in order to achieve distinct WVTR levels. In thisregard, the respective segments can be either microporous ornon-microporous films and/or filled or unfilled films utilizingdifferent polymeric compositions. In one aspect, the first segments cancomprise a filled polymeric film and second segments a filled polymericfilm comprising a polymer different from that comprising first segments,wherein upon stretching of the unitary segmented film a higher level ofbreathability is imparted to first segments relative to the WVTR of thesecond segments. As an example, first segments can comprise a linear lowdensity polyethylene (LLDPE) filled film and second segments cancomprise an elastomeric polyethylene filled film. The resultingbreathable stretched-thinned film will have first segments with a higherWVTR than second segments. The amount and/or type of filler can likewisebe varied in combination with polymer composition in order to achievethe desired WVTR, opacity and/or elasticity within the respectivesegments.

In a further aspect, unitary films with improved body conformance canalso be achieved in accord with the present invention. The segmentedfilm can comprise first and second segments wherein one of the first orsecond segments is elastic and the other segments are breathablesegments. As an example, first segments can comprise inelasticbreathable segments whereas second segments can comprise an elasticsegment. Desirably, first breathable segments comprise at least about25% of the area of segmented film and, even more desirably, comprisebetween about 50% and about 95% of the area of segmented film. Theelastic, second segments can comprise a breathable or a non-breathablefilm. As a particular example, first segments can comprise a microporousLLDPE filled film and second segments a non-porous film comprising anelastomeric polyolefin such as elastomeric polyethylene. Alternatively,second segments can comprise an elastic breathable non-porous film suchas, for example, a polyurethane, polyether ester, or polyether amidefilm. Still further, the first segment can comprise a microporouspolyolefin filled-film and the second segment can comprise aKRATON/polyolefin polymer blend.

Elastic film segments can comprise an elastomer and desirably have ahysteresis of less than 60% and more desirably a hysteresis of less thanabout 50% and still more desirably a hysteresis of less than about 40%.Inelastic segments can include those segments comprising anon-elastomeric polymer having a hysteresis of greater than about 60%.In a further aspect the elastic film segments can comprise a film of athermoplastic elastomer having a retraction/extension percent greaterthan 25 and desirably has a retraction/extension percent greater thanabout 35 and still more desirably a retraction/extension percent of atleast about 50. In this regard, inelastic film segments can comprise afilm of a thermoplastic polymer having retraction/extension ratio lessthan about 25. In a further aspect, the elastic segments desirablycomprise a thermoplastic elastomer film which, upon application of abiasing force, is elongatable, to a stretched or biased length which isat least about 160 percent of its relaxed unbiased length, and which,will immediately recover at least 55 percent of its elongation uponrelease of the elongating force. A hypothetical example would be a one(1) centimeter sample of a material which is elongatable to at least1.60 centimeters and which, upon release of the elongating force, willrecover to a length of not more than 1.27 centimeters. Manythermoplastic elastomer films exhibit greater stretch and recoveryproperties and many highly elastic materials can be stretched to 160percent of their relaxed unbiased length, and immediately recover inexcess of about 75% percent of its elongation upon release of theelongating force.

In a further aspect of the present invention, the individual filmsegments may themselves comprise either mono-layer or multi-layeredfilms. For example, the segmented film may include first segmentsincluding a multi-layered film and second segments including amono-layer film. The first segments may include one or more outer layersand one or more central or intermediate layers. In other embodimentsmulti-layered film segments can include films such as, for example,those described in U.S. Pat. No. 6,075,179 to McCormack et al.; U.S.Pat. No. 6,045,900 to Haffner et al. and U.S. patent application Ser.No. 08/882,712 filed Jun. 25, 1997 to McCormack et al., the contents ofthe aforesaid references are incorporated herein by reference.Additionally, the first and second segments may both includemulti-layered films. For example, the first segments can comprise outerlayers and a core layer and the second segments may include outer layersand a core layer. The outer layers of the first and second segments mayinclude identical, similar or different compositions. Where one or moreof the segments are elastic it is desirable that outer layers extendingover the elastic segments include an extensible layer. In this regard,when comprising a small percent of the overall film thickness, layerswhich by themselves are inelastic can still be utilized as they will notimpede the stretch and recovery provided by the elastic core layer.Desirably, however, outer layers extending over elastic segments exhibitgood extensibility. As an example, the core layer of the first segmentmay include an inelastic breathable microporous LLDPE filled film andthe core layer of the second segment may include an elastic polyolefinand the outer layers of the first and second segments may include ablend of LLDPE and EMA.

In a further aspect of the invention, the segmented film may include oneor more discrete elastic segments positioned between breathablesegments. In one embodiment, the breathable segments includesubstantially inelastic segments having high levels of breathability.For example, the segmented film may include first segments and discretesecond segments disposed there between. The discrete elastic segmentscan either be breathable or non-breathable. Desirably, the firstbreathable segments include at least about 25% of the area of thesegmented film and, even more desirably, include between about 50% andabout 95% of the area of the segmented film. In addition, discreteelastic segments may have a width (dimension in the CD of the film) ofat least 0.1 cm and desirably have a width of at least about 1 cm ormore. The width of the breathable segments separating the second elasticsegments can vary in accord with the desired attributes of the segmentedfilm; use of larger elastic segments and/or more closely groupedsegments will improve the overall stretch and recovery attributes of theunitary segmented film. The first breathable segments and the secondelastic segments may include either mono-layer or multi-layer films. Forexample, the first breathable segments may include a multi-layered filmincluding outer layers and a central core layer and the second elasticsegments may include a mono-layer film. In a particular embodiment, thefirst breathable segments may include an inelastic multilayered filmsuch as those described in U.S. Pat. No. 6,309,736 to McCormack et al.and the second elastic segments may include an elastic polyethylene. Asa further example, the first breathable segments and the second elasticsegments may both include multi-layered films with the first segmentcomprising outer layers and an intermediate layer and the second segmentcomprising outer layers and an intermediate layer. Desirably, the outerlayers of the first breathable segments and the second elastic segmentsmay include a similar or identical polymer composition such as, forexample, EMA, EEA, EVA or polyolefin blends thereof.

As indicated above, a wide variety of polymers are suitable for use withthe present invention. Polymers of adjacent segments should becompatible in the sense that they exhibit sufficient cohesion to form acontinuous, cohesive film. In this regard, utilization of polymer blendscan improve cohesion of adjacent segments. For example, polyethylene andpolypropylene are not, by themselves, compatible whereaspolyethylene/polypropylene blends can be compatible with polyethyleneand/or polypropylene segments. In a particular embodiment, a firstsegment can comprise LLDPE and a polypropylene impact copolymer (such astaught in U.S. Pat. No. 6,072,005 Kobylivker et al., the entire contentsof which are incorporated herein by reference), and an adjacent secondsegment can comprise an elastic polypropylene. Further,compatibilization may likewise be achieved through addition of one ormore bonding or tackifying resins within a segment. Exemplary bonding ortackifying resins are described in U.S. Pat. No. 5,695,868 to McCormack.In addition, compatibilization segments or tie segments can be used inorder to utilize a wider range of polymers. Accordingly, the use of acompatibilizing segment makes it possible to achieve a continuouscohesive segmented film using discrete segments of incompatiblepolymers. For example, the segmented film may include first segments andsecond segments wherein compatibilizing segments are disposed betweenthe first and second segments. As a particular example, the firstsegments may include a breathable inelastic segment comprising amicroporous LLDPE film and the second segments may include elasticpolypropylene. Compatibilizing segments may be disposed between thefirst and second segments and may include, for example, anethylene-propylene copolymer. In a further aspect, a compatibilizingsegment can itself include a bonding or tackifying resin such as anamorphous polyalphaolefins such as REXTAC from Rextac LLC and VESTOPLASTfrom Huels AG of Marl, Germany. Composition of the compatibilizingsegment can vary in accord with the desired film attributes and theparticular polymers comprising adjacent segments.

To concurrently form apertures and embossments in the segmented film,the aperturing/embossing is may be generally accomplished via feedingthe segmented film through a nip defined by at least one patterned rollsuch as described in U.S. patent application Ser. No. 12/649,427 to Ng,et al.

The segmented film may be “pre-stretched” (prior to nipping) by rollsrotating at different speeds of rotation so that the sheet is stretchedto the desired stretch ratio in the machine direction. This uniaxiallystretched film may also be oriented in the cross-machine direction toform a “biaxially stretched” film. The orientation temperature profileduring the “pre-stretching” operation is generally below the meltingpoint of one or more polymers in the film, but high enough to enable thecomposition to be drawn or stretched. For example, the film may bestretched at a temperature from about 15° C. to about 50° C., in furtherembodiments from about 25° C. to about 40° C., and in even furtherembodiments, from about 30° C. to about 40° C. When “pre-stretched” inthe manner described above, the degree of stretch during lamination maybe increased, maintained, or slightly reduced (retracted) to desireddegree of tension.

The raw materials for the first and second segments of the film areprepared and added to a hoppers of an extrusion apparatus for eachsegment. The materials are dispersively mixed in the melt and compoundedusing any known technique, such as batch and/or continuous compoundingtechniques that employ, for example, a Banbury mixer, Farrel continuousmixer, single screw extruder, twin screw extruder, etc.

Any known technique may be used to form a segmented film from thecompounded materials, including blowing, casting, flat die extruding,etc. For example, the extruded film may be blown into nip rolls to forma single-layered precursor segmented film. The rolls may be kept attemperature sufficient to solidify and quench the precursor segmentedfilm as it is formed, such as from about 20 to 60° C.

Various additional potential processing and/or finishing steps known inthe art, such as passing it through a film-orientation unit or machinedirection orienter (“MDO”), aperturing, embossing, slitting, treating,printing graphics, etc., may be performed without departing from thespirit and scope of the invention. For instance, the segmented film mayoptionally be mechanically stretched in the cross-machine and/or machinedirections to enhance extensibility. In one embodiment, the segmentedfilm may be coursed through two or more rolls that have grooves in theCD and/or MD directions. The grooved rolls may be constructed of steelor other hard material (such as a hard rubber). Such groovedsatellite/anvil roll arrangements are described in U.S. PatentApplication Publication Nos. 2004/0110442 to Rhim, et al. and2006/0151914 to Gerndt, et al., which are incorporated herein in theirentirety by reference thereto for all purposes.

The segmented films may, optionally, be laminated to one or moreadditional films and/or fabrics. For example, a segmented film describedherein may be bonded to a nonwoven web. As used herein the term“nonwoven” fabric or web means a web having a structure of individualfibers or threads which are interlaid, but not in an identifiable manneras in a knitted or woven fabric. Nonwoven fabrics or webs have beenformed by many processes such as for example, meltblowing processes,spunbonding processes, hydroentangling, air-laid and bonded carded webprocesses. As used herein the term “spunbond” refers to small diameterfibers of molecularly oriented polymeric material. Spunbond fibers aregenerally formed by extruding molten thermoplastic material as filamentsfrom a plurality of fine, usually circular capillaries of a spinneretwith the diameter of the extruded filaments then being rapidly reducedas by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S.Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 toMatsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S.Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,542,615 to Dobo et al,U.S. Pat. No. 5,382,400 to Pike et al. and in commonly assigned U.S.patent application Ser. No. 08/756,426 now allowed filed Nov. 26, 1996to Marmon et al. and U.S. application Ser. No. 08/565,261 now U.S. Pat.No. 5,759,926 filed Nov. 30, 1995 to Pike et al. As used herein the term“meltblown” or “meltblowing” refers to fine fibers of polymeric materialwhich are generally formed by extruding a molten thermoplastic materialthrough a plurality of fine, usually circular, die capillaries as moltenthreads or filaments into converging high velocity, usually hot, gas(e.g. air) streams which attenuate the filaments of molten thermoplasticmaterial to reduce their diameter. Thereafter, the meltblown fibers canbe carried by the high velocity gas stream and are deposited on acollecting surface to form a web of randomly dispersed meltblown fibers.Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 toButin et al.; U.S. Pat. No. 4,526,733 to Lau; U.S. Pat. No. 5,652,048 toHaynes et al.; and U.S. Pat. No. 5,366,793 to Fitts et al. Meltblownfibers may be continuous or discontinuous, are generally less than 10microns in average diameter, and are commonly between about 0.5 andabout 7 microns in average diameter. Nonwovens may also be multilayernonwoven laminates that include at least one layer of a nonwoven weband/or multiple nonwoven layers such as, for example, aspunbond/meltblown/spunbond (SMS) laminate. Examples of multilayernonwoven laminates are disclosed in U.S. Pat. No. 4,041,203 to Brock etal., U.S. Pat. No. 5,178,931 to Perkins et al. and U.S. Pat. No.5,188,885 to Timmons et al.

The particular composition of any additional layers attached to thesegmented film may be selected to achieve desired attributes such as,for example, aesthetics, strength, durability, hand, etc. As examples,segmented films can be laminated to knitted fabrics, nonwoven fabrics,foams, scrims, multilayered nonwoven laminates, and so forth. As usedherein, the term “scrim” means a lightweight fabric used as a backingmaterial. Scrims are often used as the base fabric for coated orlaminated products. The segmented film and other fabric(s) can belaminated together by means known to those skilled in the art such as,for example, by thermal bonding, ultrasonic bonding, adhesive bondingand the like. Thermal point bonding is an exemplary means of laminatingthe respective layers. As used herein “point bonding” means bonding oneor more layers of fabric at a plurality of discrete bond points. Forexample, thermal point bonding generally involves passing one or morelayers to be bonded between heated rolls such as, for example anengraved pattern roll and a smooth calender roll. The engraved roll ispatterned in some way so that the entire fabric is not bonded over itsentire surface, and the anvil roll is usually flat. As a result, variouspatterns for engraved rolls have been developed for functional as wellas aesthetic reasons. One example of thermal point bonding is describedin U.S. Pat. No. 3,855,046 to Hansen et al. Numerous other bondingpatterns are known such as, for example, those described in U.S. DesignPat. No. 356,688 to Uitenbroek et al. and U.S. Pat. No. 5,620,779 toLevy et al.

Where one or more of the segments within the segmented film comprises anelastic segment, any additional layers laminated thereto desirablycomprise an extensible material or fabric. In this regard, theadditional layer or layers can comprise, as examples, extensiblenonwoven materials (e.g. creped nonwovens or nonwovens comprising highlycrimped fibers), meshed fabrics, loosely woven fabrics, elasticcomposite materials and/or other like materials. Desirably the fabriccomprises one or more layers of thermoplastic fibers which are elastic,inherently extensible or which have been treated so as to be becomeextensible and/or elastic and which also have a cloth-like hand anddrape. Examples of suitable extensible and/or elastic materials aredescribed in U.S. Pat. No. 4,965,122 to Morman et al.; U.S. Pat. No.U.S. Pat. No. 5,114,781 to Morman et al.; U.S. Pat. No. 5,336,545 toMorman et al.; U.S. Pat. No. 4,720,415 to Vander Wielen et al.; U.S.Pat. No. 4,789,699 to Kieffer et al.; U.S. Pat. No. 5,332,613 to Tayloret al.; U.S. Pat. No. 5,288,791 to Collier et al.; U.S. Pat. No.4,663,220 to Wisneski et al.; U.S. Pat. No. 5,540,976 to Shawver et al.;European Application No. 0,712,892 A1 to Djiaw et al.; U.S. Pat. No.5,952,252 to Shawver et al.; U.S. Pat. No. 5,714,107 to Levy et al.; andU.S. Pat. No. 6,054,002 to Griesbach et al.; the contents of theaforesaid references are incorporated herein by reference. Thecomposition of the thermoplastic polymer may be selected as desired toachieve a material having the desired physical attributes such as, forexample, elasticity, hand, tensile strength, cost and so forth. Further,the outer nonwoven layer may be treated such as, for example, byembossing, hydroentangling, mechanically softening, printing,anti-static treatment or treated in some other manner in order toachieve desired aesthetics and/or functional characteristics.

The segmented films of the present invention, and laminates thereof, canbe utilized in a wide variety of applications such as, for example, inpersonal care articles, infection control products, protective apparel,protective covers, garments and so forth. As used herein, the term“personal care product” means personal hygiene oriented items such asdiapers, training pants, absorbent underpants, adult incontinenceproducts, feminine hygiene products, and the like. As used herein, theterm “infection control product” means medically oriented items such assurgical gowns and drapes, head coverings like bouffant caps, surgicalcaps and hoods, industrial workwear, footwear like shoe coverings, bootcovers and slippers, wound dressings, bandages, sterilization wraps, labcoats, coveralls, aprons and so forth. As used herein, the term“protective apparel” means industrial related apparel or garments suchas coveralls, aprons, workwear, coveralls and so forth. As used herein,the term “protective cover” means a cover for vehicles such as cars,boats, airplanes, etc., covers for articles or equipment often leftoutdoors (e.g. grills and lawn furniture), yard and garden equipment,floor coverings, tents and the like. As used herein, the term “garment”means any type of non-medically or non-industrial oriented apparel whichmay be worn. This includes coveralls, undergarments, pants, shirts,jackets, gloves, socks, and the like.

Further, it will be appreciated by those skilled in the art that thesegmented films of the present invention can be advantageously utilizedin numerous other applications employing breathable barrier fabrics. Asused herein, the term “barrier” means a film, laminate or other fabricwhich is relatively impermeable to the transmission of liquids and whichhas a hydrohead of at least about 50 mbar. Hydrohead as used hereinrefers to a measure of the liquid barrier properties of a fabricmeasured in millibars (mbar). However, it should be noted that in manyapplications of barrier fabrics, it may be desirable that they have ahydrohead value greater than about 80 mbar, 150 mbar or even 200 mbar.In one embodiment, the embossed segment of the segmented film may have ahigher hydrohead value than the apertured segment. Advantageously, theembossed segment may be used in an area of the product that requiresgood barrier properties, while the apertured segment may be used in anarea of the product that requires more breathability.

As a particular example, segmented films of the present invention can bereadily converted and incorporated within a breathable barrier of adiaper or incontinence garment. Although the breathability provided bymicroporous films and/or laminates thereof is advantageous in manyarticles, there exist some situations where high breathability can beundesirable. For example, in personal care articles such as diapers orincontinence garments the breathable barrier and absorbent coregenerally work together to retain bodily fluids discharged into thegarment. However, when fluid is retained within the absorbent coresignificantly higher levels of water vapor begin to pass through thebreathable barrier. The increased levels of water vapor passing throughthe outer cover can form condensate on the outer portion of the garment.The condensate is simply water but can be perceived as leakage. Inaddition, the condensate can create a damp uncomfortable feel to theouter portion of the garment which is unpleasant for those handling thearticle. Providing a breathable barrier which has a lower WVTR in suchregions, while providing good breathability in the remaining regions,would provide a garment with excellent wearer comfort yet which limitsthe potential for outer cover dampness. In this regard, as discussed ingreater detail herein below, segments having relatively high and lowbreathability can be strategically positioned within absorbent articlesto help reduce and/or eliminate outer cover dampness. In a furtheraspect, the present invention provides films having stretch and recoveryin the CD direction thereby providing a film and/or articleincorporating the same, with excellent body conformance attributes.Moreover, excellent body conformance can be achieved without significantloss of breathability or loss of barrier properties.

Personal care articles generally include a liquid permeable topsheet,which faces the wearer, and a liquid-impermeable bottom sheet or outercover. Disposed between the topsheet and outer cover is an absorbentcore. Often the topsheet and outer cover are sealed to encase theabsorbent core. The segmented films and film laminates of the presentinvention are particularly well suited for use as an outer cover of apersonal care article. Exemplary personal care articles are described,by way of examples only, in the following references: U.S. Pat. No.5,415,644 to Enloe et al.; U.S. Pat. No. 4,798,603 to Meyer et al.; U.S.Pat. No. 5,810,797 to Menard et al.; U.S. Pat. No. 4,641,381 to Herrenet al.; U.S. Pat. No. 4,701,175 to Boland et al.; and U.S. Pat. No.4,938,797 to Van Gompel et al.; the entire content of the aforesaidreferences are incorporated herein by reference. In addition, althoughthe following detailed description is made in the context of adisposable diaper, one skilled in the art will appreciate that theconcepts of the present invention would also be suitable for use inconnection with other types of absorbent articles, particularly otherpersonal care products. In addition, although the present invention isdescribed in the context of several specific configurations, it will beappreciated that further combinations or alterations of the specificconfigurations discussed below may be made by one skilled in the artwithout departing from the spirit and scope of the present invention.

For example, a baffle for a diaper or incontinence garment may include acontinuous segmented film including a first segment and second segmentshave an interface as described herein. The baffle can be converted fromthe segmented film wherein the “ears” of the diaper correspond withsecond regions and the central portion of the article corresponds to oneor more first segments. The first segment desirably comprises abreathable film, such as for example a monolithic film or a mono-layeror multi-layered microporous film which can be elastic or inelastic. Thesecond segments desirably comprise an elastic segment with excellentstretch and recovery properties, such as for example, film segmentscomprising elastic polyurethane or KRATON/polyolefin blends. In afurther example, the segmented film may be converted such that thesegments run across the width of the article as opposed to the length ofthe article. When the segments run across the width of the article, thefirst region may include a breathable film corresponding to the centralportion of the article and the second regions may include an elasticsegment corresponding with the “waist” of the article.

Segmented films and/or laminates thereof may likewise be converted intosurgical gowns, protective workwear and the like. In this regard,medical apparel is often required to provide a higher degree ofprotection to the wearer such as, for example, preventing penetration ofblood and/or blood-borne pathogens. By comprising a segmented continuousfilm, good stretch and body conformance can be achieved without loss ofthe desired barrier properties in the desired areas. For example,surgical gowns or workwear may include breathable barrier first segmentshaving excellent WVTRs barrier properties and the second segments mayinclude elastic apertured segments and provide the garment withadditional improved stretch, body conformance attributes, andbreathability where barrier is not required.

While various patents and other reference materials have beenincorporated herein by reference, to the extent there is anyinconsistency between incorporated material and that of the writtenspecification, the written specification shall control. In addition,while the invention has been described in detail with respect tospecific embodiments thereof, it will be apparent to those skilled inthe art that various alterations, modifications and other changes may bemade to the invention without departing from the spirit and scope of thepresent invention.

EXAMPLES

Example films having three segments were produced to demonstrate theinvention. The sample films were produced from a Randcastle film dieconfigured for making segmented films. The film die had a main centerfeed port and a side edge port at the die end plate was used. The sideedge port was positioned 1.5 inches upstream from the die lip where thesegmented film exits the film die. A feed block configured for makingsegmented films with entry ports for two polymers was connected to thecenter feed port. The feed block was positioned 10.5 inches upstreamfrom the die lip where the segmented film exits the film die. A firstpolymer composition was used to create the center segment of the film. Afirst extruder (twin screw Leistritz, 27 mm) was used to melt the firstpolymer composition and feed it to one of the feed ports on the feedblock. A second polymer composition was used for the edge segments. Asecond extruder (single screw 1.25″ Killion extruder) was used to meltthe second polymer composition. After exiting the second extruder, thesecond polymer composition was split into two flows using a “Y” blockand two 8′ heated polymer hoses set to the same temperature. One flowstream was fed to one of the side edge ports of the film die. The secondflow stream was fed to the second feed port on the feed block. Theresultant film had a center segment of the first polymer compositionwith two edge segments of the second polymer composition.

Various first and second polymer compositions were used to generate fivefilms as shown in Table 1. In Table 1, “Kraton” is 68 wt. %styrene-ethylene-butylene-styrene block copolymer (KRATON® MD6937,available from Kraton Polymers), 20 wt. % tackifier (REGALREZ™ 1126,available from Eastman Chemical) and 12 wt. % polyethylene wax (EPOLENE™C-10, available from Eastman Chemical). “PE” is 70 wt. % polyethylene(DOWLEX™ 2047G, available from The Dow Chemical Company) and 30 wt. %CaCO₃ concentrate (25 wt. % polyethylene (DOWLEX™ 2047G) and 75 wt. %CaCO₃). “PP-PE” is 70 wt. % polypropylene (PP3155 available fromExxonMobil Chemical Company) and 30 wt. % CaCO₃ concentrate (25 wt. %polyethylene (DOWLEX™ 2047G) and 75 wt. % CaCO₃). “PP” is 100 wt. %polypropylene (PP3155).

Process Conditions:

Twin screw extruder conditions: Zone1: 178 C, Zone2: 187 C, Zone 3: 187C, Zone 4: 180 C, Zone 5: 181 C, Zone 6:187 C, Zone 7: 197 C, Zone 8;200 C, Flange: 200 C, Hose: 410 F, screw speed: 300 rpm, melt pressure:800 psi.

Single screw Killion Extruder conditions: Zone1: 350 F, Zone 2: 390 F,Zone 3: 420 F, Flange and Melt Pump: 420 F, Melt Pump: 25 rpm, meltpressure: 500 psi, “Y” block 420 F, hoses from “Y” block 420 F.

Die, feedblock and end plate temperature settings: 420 F.

Winder speed: 20 fpm.

Tensile testing was done on the samples produced. Tensile testing may bedone on a Sintech Corp. constant rate of extension tester 2/S with acomputer-based data acquisition and frame control system or equivalentwith an appropriate load cell so that the peak load falls between 10 and90 percent of the full-scale load of the load cell (Sintech Corp, ofCary, N.C.). The tests were conducted under ambient conditions. Fortesting the strength of a single seam, the sample size was 3 inches inthe cross-machine direction by 6 inches in the machine direction withthe seam in generally in the middle of the sample. The grip size was 3inches in width. The grip separation (gage length) was 4 inches at thestart of the test. For testing the strength of both edge seams in asingle test, the sample size and gage length were extended such thatboth edge seams were between the jaws of the grips. Samples were pulledto break at a speed of 12 inches per minute. Peak load, elongationpercent at peak load (as percentage of gage length), and energy at break(area under the load-elongation curve from the origin to the point ofrupture) were recorded.

In general, the seams created by introducing the edge polymer throughthe feedblock were found to be stronger (higher peak load and energy)than the edge seams created by introducing the edge polymer through theedge port. For the film in Ex. 1, the center segment polymer compositionwas similar to the edge segment polymer compositions, which is believedto have contributed to the seams of that film having similar strengths.It is noted, though, that when both seams were tested at the same time,the edge seam created by feeding the edge polymer composition throughthe edge port was the seam to fail.

TABLE 1 1st (center) polymer composition // 2^(nd) Feedblock Seam EdgePort Seam (edges) Peak Peak polymer Load Energy Load Energy composition(gf) Elongation % (g-cm) (gf) Elongation % (g-cm) Ex. 1 PP-PE // PP17745 6.3 5002 18922 4.2 2792 Ex. 2 PP-PE // 6613 305 57245 1799 12813737 Kraton Ex. 3 PE // PP-PE NA NA NA NA NA NA Ex. 4 PE // PE NA NA NANA NA NA Ex. 5 Kraton // PE 6952 638 154406 4676 260 44078 Test donesimultaneously Peak Load Energy (gf) Elongation % (g-cm) Comment Ex. 1PP-PE // PP 15136 56.4 4240 break at edge port side Ex. 2 PP-PE // 86480.4 13763 break at edge port Kraton side Ex. 5 Kraton // PE 3200 33483720 no break, but weakness appeared at the edge port side

Of note, for Examples 3 and 4 above, the film edge port seam splitduring production of the film, so no tensile testing was possible.

SEM photos of the seams for Example 5 are shown in FIGS. 2 and 3. FIG. 2is an SEM photo of the edge port seam. FIG. 3 is an SEM photo of thefeedblock seam. In each photo, the second (edge) segment 14 extends pastor overlaps the first (center) segment 12 to a tip 22 of the secondsegment. It is evident from the SEM photos that the feedblock seamextends much further than the edge port seams, as further evidenced bycalculations of T/t made for the two photos. T/t for the edge port seamshown in FIG. 2 was 2.6 (50/19). T/t for the feedblock seam shown inFIG. 3 was 25 (75/3).

The thicknesses “T” and “t” are measured from SEM photographs of crosssections of segmented films showing the tip of the seam between twosegments of the film. The SEM photographs, as in FIGS. 2 and 3, areprepared as follows. A sample may be cut into a lengthwise strip andmarked at the cut ends. The strip is then placed in liquid nitrogen andallowed to equilibrate for at least two minutes. The sample is thenbisectioned with a fresh single edged razor against a stainless steelbackplate while still immersed in the liquid nitrogen. The blade isallowed to chill for around 5 to 10 seconds prior to making the cut.

The sample is then mounted on a 25 mm SEM mount (specimen stub) betweensmall bars of aluminum such that the cut surface is horizontal. Thesample is then exposed to ruthenium tetraoxide vapors for a period of 1hour. The sample is allowed to outgas overnight and then is evaluated inthe scanning electron microscope with no additional treatment orcoating. The ruthenium stain reacts with cyclic unsaturation causingcompounds with styrenic functionality to be aggressively stained. Whenan organic material is stained with a heavy metal, the backscattercoefficient increases causing the backscatter signal to increase,resulting in brighter image details. Since the secondary electron imagehas a backscatter component, this brightening effect from the stain isoften seen in these images as well.

A Hitachi S-4500 field emission scanning electron microscope, orequivalent, may be used to evaluate the surface of the cross-section atlow voltage (800-1200 volts) using both a microchannel plate(backscattered) and secondary electron detectors at magnifications of100 to 1,000 times. Digital images may be acquired using a Quartz PCIimage acquisition system, or equivalent, that is interfaced to themicroscope. The Quartz PCI software, or equivalent, can also be used tomake thickness and other measurements.

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto. As used herein, the term “comprising” is inclusive oropen-ended and does not exclude additional unrecited elements,compositional components, or method steps. In addition, it should benoted that any given range presented herein is intended to include anyand all lesser included ranges. For example, a range of from 45-90 wouldalso include 50-90; 45-80; 46-89 and the like.

What is claimed is:
 1. A method of forming a segmented film, the methodcomprising: providing first and second polymer compositions to asegmented feedblock; transferring the first and second polymercompositions to a film die and wherein the first and second polymercompositions contact each other and flow together substantially in across-direction prior to exiting the film die; co-extruding a segmentedfilm comprising a first film segment of the first polymer compositionand a second film segment of the second polymer composition and a seamhaving an interface formed from the joinder and overlap of the first andsecond polymers in the cross-direction, and further wherein the seam isbetween the first and second film segments and the first film segment,second film segment and seam extend adjacent one another continuously inthe machine-direction, and wherein at the interface a tip of the secondfilm segment overlaps the first film segment in the cross-direction ofthe film, and wherein the film has a thickness “T” at the tip of thesecond film segment, and the second film segment has a thickness “t” ata distance T in the cross direction from the tip of the second filmsegment, and wherein the ratio T/t is greater than
 10. 2. The method ofclaim 1, wherein the ratio T/t ranges from 10 to about
 100. 3. Themethod of claim 1, wherein the first and second polymer compositionsflow together in the film die substantially in a cross direction priorto exiting the film die in a machine direction.
 4. The method of claim 3wherein the first and second polymer compositions contact each otherprior to entering the film die.
 5. The method of claim 4 wherein theratio T/t is between 10 and
 50. 6. The method of claim 2 wherein theratio T/t is between 10 and 30.